------------[ cut here ]------------
WARNING: CPU: 1 PID: 3828 at net/ipv4/af_inet.c:167 inet_sock_destruct+0x598/0x760 net/ipv4/af_inet.c:167
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 3828 Comm: syz-executor003 Not tainted 4.9.123-g7fa8c15 #28
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801db307cc0 ffffffff81eb9689 ffffffff83c48ac0 00000000ffffffff
 0000000000000000 0000000000000001 00000000000000a7 ffff8801db307d80
 ffffffff81423f75 0000000041b58ab3 ffffffff843bb880 ffffffff81423db6
Call Trace:
 <IRQ> [   34.999530]  [<ffffffff81eb9689>] __dump_stack lib/dump_stack.c:15 [inline]
 <IRQ> [   34.999530]  [<ffffffff81eb9689>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff81423f75>] panic+0x1bf/0x3bc kernel/panic.c:179
 [<ffffffff81424261>] __warn.cold.9+0xc1/0x17f kernel/panic.c:542
 [<ffffffff811383bc>] warn_slowpath_null+0x2c/0x40 kernel/panic.c:585
 [<ffffffff8342c878>] inet_sock_destruct+0x598/0x760 net/ipv4/af_inet.c:167
 [<ffffffff836c5bb9>] l2tp_tunnel_destruct+0x339/0x590 net/l2tp/l2tp_core.c:1329
 [<ffffffff830281f5>] __sk_destruct+0x55/0x590 net/core/sock.c:1428
 [<ffffffff81289aae>] __rcu_reclaim kernel/rcu/rcu.h:118 [inline]
 [<ffffffff81289aae>] rcu_do_batch kernel/rcu/tree.c:2789 [inline]
 [<ffffffff81289aae>] invoke_rcu_callbacks kernel/rcu/tree.c:3053 [inline]
 [<ffffffff81289aae>] __rcu_process_callbacks kernel/rcu/tree.c:3020 [inline]
 [<ffffffff81289aae>] rcu_process_callbacks+0x8ae/0x12b0 kernel/rcu/tree.c:3037
 [<ffffffff83a08980>] __do_softirq+0x210/0x940 kernel/softirq.c:288
 [<ffffffff8114d554>] invoke_softirq kernel/softirq.c:368 [inline]
 [<ffffffff8114d554>] irq_exit+0x114/0x150 kernel/softirq.c:409
 [<ffffffff83a07561>] exiting_irq arch/x86/include/asm/apic.h:669 [inline]
 [<ffffffff83a07561>] smp_apic_timer_interrupt+0x81/0xa0 arch/x86/kernel/apic/apic.c:962
 [<ffffffff83a036f0>] apic_timer_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:648
 <EOI> [   35.121891]  [<ffffffff814bbb8b>] ? __anon_vma_interval_tree_compute_subtree_last mm/interval_tree.c:72 [inline]
 <EOI> [   35.121891]  [<ffffffff814bbb8b>] ? __anon_vma_interval_tree_augment_propagate mm/interval_tree.c:72 [inline]
 <EOI> [   35.121891]  [<ffffffff814bbb8b>] ? __rb_erase_augmented include/linux/rbtree_augmented.h:249 [inline]
 <EOI> [   35.121891]  [<ffffffff814bbb8b>] ? rb_erase_augmented include/linux/rbtree_augmented.h:257 [inline]
 <EOI> [   35.121891]  [<ffffffff814bbb8b>] ? __anon_vma_interval_tree_remove mm/interval_tree.c:72 [inline]
 <EOI> [   35.121891]  [<ffffffff814bbb8b>] ? anon_vma_interval_tree_remove+0x51b/0xe30 mm/interval_tree.c:89
 [<ffffffff814f7b58>] unlink_anon_vmas+0x198/0x5b0 mm/rmap.c:386
 [<ffffffff814c71f6>] free_pgtables+0xe6/0x330 mm/memory.c:552
 [<ffffffff814e4cc3>] exit_mmap+0x223/0x3f0 mm/mmap.c:3022
 [<ffffffff8112db63>] __mmput kernel/fork.c:884 [inline]
 [<ffffffff8112db63>] mmput+0xf3/0x2d0 kernel/fork.c:906
 [<ffffffff81143096>] exit_mm kernel/exit.c:514 [inline]
 [<ffffffff81143096>] do_exit+0x906/0x27b0 kernel/exit.c:820
 [<ffffffff81149251>] do_group_exit+0x111/0x340 kernel/exit.c:937
 [<ffffffff8114949d>] SYSC_exit_group kernel/exit.c:948 [inline]
 [<ffffffff8114949d>] SyS_exit_group+0x1d/0x20 kernel/exit.c:946
 [<ffffffff81006316>] do_syscall_64+0x1a6/0x490 arch/x86/entry/common.c:282
 [<ffffffff83a01d93>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..